Suspension of a sample element with dimensional stability

Abstract

Substrates for suspending sample elements are disclosed, as well as sample platforms comprising such substrates, in which the sample elements can be analyzed with improved reliability. In exemplary embodiments, such sample elements are used in thermoluminescence dosimeters (TLDs) or optically stimulated luminescence dosimeters (OSLDs) to provide a calculated radiation dose with improved accuracy. The reproducibility associated with analyzing a sample element, and particularly one suspended by a film or encapsulated within films, may be significantly improved by tensioning the film(s). Tensioning may result during assembly of a sample platform, using a mechanical creasing force that is applied as the result of the configuration of a substrate of the sample platform, such as opposing sections or plates of this substrate. Alternatively, tensioning may be achieved using a separate application of force to the film(s) against a section or plate of the substrate.

What is claimed is: 
     
       1. A substrate for suspending a sample element, the substrate comprising top and bottom sections that are configured, upon alignment, to form a substrate opening and engage an outer region of a film that is external to a central region extending across the opening;
 wherein the top and bottom sections are further configured to mechanically tension the central region of film across the opening by displacement of the film along an edge of the opening formed in part by an extension element of the bottom section that is angled in a direction that is offset from a plane of the opening, and wherein the alignment of the top and bottom sections provides a chamfer in the opening. 
 
     
     
       2. A sample platform comprising:
 a substrate having a plurality of openings across each of which a central region of a film extends, and 
 a plurality of sample elements each suspended by the central region of the film within one of the openings, 
 wherein each of the central regions of the film is tensioned across the respective opening to reduce movement of the respective sample element upon heating. 
 
     
     
       3. The sample platform of  claim 2 , wherein the substrate comprises four openings and the sample platform comprises four sample elements, each sample element comprising a different thermoluminescent material type or material mass density for measuring differing types of ionizing radiation. 
     
     
       4. The sample platform of  claim 2 , wherein each of the central regions of the film is tensioned across the respective opening by displacement of the film in a direction that is offset from a plane of the respective opening. 
     
     
       5. The sample platform of  claim 4 , wherein the displacement occurs along an edge of the respective opening. 
     
     
       6. The sample platform of  claim 5 , wherein the displacement results from a crease in the film at the edge of the respective opening. 
     
     
       7. The sample platform of  claim 6 , wherein the crease is formed upon alignment of a top section of the substrate with a bottom section of the substrate having an extension element. 
     
     
       8. The sample platform of  claim 1 , wherein the opening is circular. 
     
     
       9. The sample platform of  claim 8 , wherein the opening has a diameter from about 5 millimeters (mm) to about 30 mm. 
     
     
       10. A method for determining a radiation dose, the method comprising:
 reading a sample element of a sample platform by exposure of the sample element to heat or light, and 
 measuring the intensity of electromagnetic radiation emitted by the sample element; 
 wherein the sample platform comprises a substrate comprising top and bottom sections that are configured, upon alignment, to form a substrate opening and engage an outer region of a film that is external to a central region extending across the opening; 
 wherein the top and bottom sections are further configured to mechanically tension the central region of film across the opening. 
 
     
     
       11. The method of  claim 10 , wherein movement of the sample element during the reading is reduced, relative to a reference method in which the central region of the film is not tensioned. 
     
     
       12. The method of  claim 11 , wherein the movement of the sample element that is reduced is a downward movement or a twisting movement. 
     
     
       13. The method of  claim 10 , wherein the reading of the sample element is by exposure of the sample element to heat, according to a time-temperature profile. 
     
     
       14. The method of  claim 13 , wherein the time-temperature profile includes a maximum temperature of at least about 150° C. 
     
     
       15. The method of  claim 10 , wherein the reading of the sample element is by exposure of the sample element to light, wherein the light has a first wavelength that differs from a second wavelength of the electromagnetic radiation emitted by the sample element. 
     
     
       16. A method of making a dosimetry card, the method comprising:
 affixing an outer region of a film to a first plate of a substrate, in a manner such that a central region of the film, which supports a sample element, extends across a first plate opening; 
 aligning a second plate opening of a second plate with the first plate opening to form a substrate opening; 
 wherein the film is tensioned across the substrate opening by creasing the film at an edge of the substrate opening and the dosimetry card is a thermoluminescence dosimetry (TLD) card or an optically stimulated luminescence dosimetry (OSLD) card. 
 
     
     
       17. The method of  claim 16 , wherein the film is tensioned by creasing the film against the first plate of the substrate, prior to the aligning of the second plate opening with the first plate opening. 
     
     
       18. The method of  claim 16 , wherein the creasing is performed upon the aligning of the second plate, by an extension element of the second plate that protrudes radially inward, to a greater extent relative to the first plate opening.